Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/fce006601489
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #12013 from snowmantw/issue913377

Bug 913377 - Redesign of lockscreen implementation, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/2855f5d28639
Author: Greg Weng (snowmantw) <gweng@mozilla.com>
Desc: Bug 913377 - Redesign of lockscreen - Gaia implementation